Playing favorites with your children is dangerous. One of the keys to successful parenting is to affirm the unique character in each of your children without being preferential to one in particular.
While Jacob was growing up, his mother favored him while his father favored his twin brother, Esau (see Genesis 25:28). Their favoritism led to all kinds of competition and trouble. In this passage Jacob (called Israel) favors Joseph, his youngest son. And the sibling rivalry that this favoritism inspires will soon break Jacob’s heart.
Taken from NIV The Journey Bible